The present invention relates to an arrangement for moving a body in a three dimensional space, wherein the body is pivotably connected to connecting arms which each have at least two degrees of freedom and are provided with at least one drive for controlling an active degree of freedom.
It is known to move the platforms of so-called octahedral machines with six telescopic legs. They allow the movement in six independent degrees of freedom. The telescopic legs are supported by ball-and-socket joints or universal joints and are driven by threaded spindles, planetary rolling spindles or linear direct drives. The drives are integrated for this purpose into the telescopic legs. The telescopic legs define a triangular area between their end points at the platform and a stationary frame part. The joints are arranged at the stationary frame such that the connecting lines, formed by the base line of the triangular areas, define a hexagon.
Six telescopic legs are needed for movement of a platform in six degrees of freedom only when per telescopic leg only one drive for one active degree of freedom is integrated. When, for example, two drives for two active degrees of freedom are integrated per telescopic leg, the number of telescopic legs is reduced to three.
The end point of each telescopic leg is moveable in the three degrees of freedom X, Y, Z. Devices with rotatable but stationary base points and motorically displaceable, longitudinally adjustable legs or motorically adjustable base points and motorically longitudinally adjustable legs are know. In order to realize arrangements with less than six degrees of freedom for the platform, it has been suggested to use parallelogram arrangements for locking degrees of freedom as, for example, parallelograms for locking all orientational directions for stationary base points of the legs or also for position-adjustable base points in the form of hexa glides.
A feature of all known rod kinematic arrangements for machine-technological applications is the use of a platform as a tool carrier or work piece carrier.
In addition to the advantage of a mass-reduced movement apparatus, which is especially suitable for high accelerations, this arrangement however has considerable disadvantages. The ability for orientational changes is limited for hexapod devices in general to less than 30.degree. because for greater orientational changes the legs will obstruct one another. The plurality of joints in each system results in a plurality of non-linear yielding positions which can only be linearly aligned by providing a respective prestress. Due to the geometric arrangement, this prestress cannot be provided by the connecting arms themselves, but only with prestress of each individual bearing.
It is therefore an object of the present invention to embody the device of the aforementioned kind such that, while providing high precision, a greater angle is possible for orientational changes.